This is Dr Basu, experienced Internal Medicine Specialist.
I am here to address your concerns and provide great service.
Viral infection or flu is still more likely given the 1 week duration.
Also you do not notice any blood in stool or fever.
So bacterial infection unlikely.
Parasitic infection is still possible though.
Stool tests are recommended.
Weight gain can be due to the metabolic disorder like thyroid gland problem, menopause, diabetes.
Hence fasting blood tests to check serum TSH, free t4, fasting blood sugar, a1c levels required.
You should consider following low fermentable sugar diet ( FODMAP diet) to reduce your symptoms.
Please go to this link for detailed information:
Please also include prebiotics like Inulin daily to keep your colon acidic which prevent gas producing bacteria.
Also take a probiotic ( lactobacilli, bifidobacterium) daily to restore intestinal microbial balance.
Culturelle 30 Counts twice daily should be fine.
Simethicone and activated charcoal can be taken before meals to reduce gas and bloating.
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